The invention concerns a method for continuous casting and rolling at increased casting speed followed by hot rolling of relatively thin metal strands, especially steel strands, into thin, hot-rolled strip in a multiple-stand hot-strip finishing train with automatic control of the temperatures of the work rolls, and a continuous casting and rolling installation for carrying out this method.
Rolling at (high) casting speeds, i.e., the coupling of a continuous casting plant and a hot-strip finishing train, leads to relatively low conveying speeds within the hot-strip finishing train downstream of the continuous casting plant. Despite high initial temperatures (e.g., about 1,250° C.), a required final rolling temperature of more than 850° C. cannot be maintained under ordinary conditions due to temperature losses to the environment and to the work rolls. Large amounts of energy are transferred to the work rolls.
The aforesaid ordinary conditions exist, for example, in a continuous casting plant that allows high casting speeds and provides high initial temperatures for the hot-strip finishing train.
It is also well known (DE 198 30 034 A1) that the temperature of the work rolls can be automatically controlled with cross-field inductors and the use of a computer model that incorporates strip width, material values, draft per pass, rolling speed, rolling temperatures, and roll cooling. However, the result is used for automatic control of the temperatures in the peripheral regions to be adjusted in the work rolls and the rolled strip.
It is also known (EP 0 415 987 B2) that so-called thin slabs (cast strands about 50 mm thick) can be inductively heated again in individual rolling steps before and within the finishing train, which requires a large amount of electric power.
It has also already been proposed that the diameters of the work rolls be reduced to reduce the heat flux into the rolls.